256 Un. UEALEj ON THE TISSUES. 



the conversion of formed material intothe secretion — isbrought 

 about in tissues distant from such surfaces as the muscles, 

 nerves, and some other textures, by the little masses of active 

 germinal matter known as the lymph and white blood-cor- 

 puscles, and thus the debris is again restored to the blood, to 

 be resolved into matters which may serve as pabulum, and com- 

 pounds which must be eliminated. 



An abnormal or morljid growth may originate in any tissue 

 in the body. If it commences in a tissue of simple forma- 

 tion, it will retain, to a great extent, the character of this 

 structure, but if it arise in one of the higher tissues it will 

 soon become so modified that it would not be possible to de- 

 termine its origin from its microscopical characters. 



The character of a morbid growth will, therefore, in great 

 measure, depend upon the tissue in which it originated. Not 

 unfrequently it would be quite impossible to distinguish a sec- 

 tion of a morbid growth from one of the healthy tissue in 

 which it commenced. In other cases an important modifica- 

 tion in the elementary parts will have taken place. The mus- 

 cular fibre-cells around the pylorus, and in other parts of the 

 intestinal canal, sometimes increase enormously in number, 

 leading to the formation of a firm, unyielding tissue, which is 

 almost as firm as fibro-cartilage (sometimes described as scir- 

 rhus of the pylorus) . As the contractile element increases 

 it loses its contractile power, and the whole mass appears to 

 be composed of a form of fibrous tissue, in Avliich the separate 

 fibres are very distinct, and arranged parallel to each other in 

 concentric layers. 



A specimen of the uterus of the mouse, in which the con- 

 tractile elementary parts of organic muscle are seen, at the 

 margin of the bundles, to shade into those of fibrous tissue, 

 was shown. Up to a certain period the germinal matter of 

 these might have produced organic muscle, but the contrac- 

 tile tissue not being produced, a lower form of tissue is^ as it 

 v.'cre, formed in its stead. Since such a transition may be 

 demonstrated in the healthy state, we shall not be surprised 

 at finding what amounts to a very exaggerated change in dis- 

 ease. The elementary parts have multiplied enormously, but 

 they have developed, not their characteristic contractile tissue, 

 but a lower and simpler form o^ formed material, not possess- 

 ing the peculiar endowments of the normal structure. 



If the restrictions under which a soft, healthy tissue grows 

 be removed, a soft and often very rapidly groAving structure 

 results. 



Those structures which in the healthy organism growfastest, 

 and pass most rapidly through the various stages of their 



